Digital/electron logic and electromechanical control for stringed musical instruments

ABSTRACT

A stringed musical instrument having individual solenoids controlling dampers for the various strings. Chords can be played by energizing selected solenoids. Push-button switches are employed in conjunction with digital logic circuits to provide rapid selection of combinations of solenoids to be simultaneously energized, to thereby provide rapid selection of chords.

151 3,682,036 51 Aug. 8, 1972 United States Patent Null et al.

a m m nmm ms [54] DIGITAL/ELECTRON LOGIC AND ELECTROMECHANICAL CONTROL FOR STRINGED MUSICAL, INSTRUMENTS 2,744,433 5/1956 Roomsm...

a m m n m H mm m. 6 w r n nrm a 3 a 0 t Wm 7 m 3 w n 3 P M B m XnS e w w i 3 fifluwa 7 mm 9 WV weft SS m 2mm, ....8e d v -m CMHD m n e V m H U Attorney-Barman, Davidson and Berrnan [22] Filed: June 18, 1971 ABSTRACT [21 Appl, No.: 154,365

chords.

10 Claims, 9 Drawing Figures PATENTEDAUI; 81972 3.682.036

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A TTORNEYS.

ing the required fingering actions to produce desired chords.

A main object of the invention is to provide a novel and improved stringed musical instrument having electromechanical means to select desired chords, with the electromechanical means involving relatively simple components, being very easy to operate, and employing digital logic circuits for the selection of the desired chords.

A further object of the invention is to provide an improved stringed instrument having semiautomatic electronic control means for controlling the vibration of its individual strings, the control means providing greatly increased range of chord selection without a corresponding change in physical size or shape of the instrument, and said control means further simplifying the selection of string combinations and making the selection more rapidly and easily available than devices previously employed for this purpose.

A still further object of the invention is to provide an improved electromechanical control system for selecting chords to be played by stringed musical instrument, the system being applicable either to stringed instruments of the type wherein the strings are normally damped or wherein the strings are normally free to vibrate, the improved control means of the present in vention allowing the musician or operator either to rapidly select a desired combination of strings to be released or, in the case of the latter type of stringed musical instrument, to produce damping of selected strings at selected positions thereon.

Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:

FIG. 1 is a perspective view of an auto-harp provided with improved chord-selecting means according to the present invention.

FIG. 2 is an enlarged fragmentary transverse vertical cross-sectional view taken substantially on the line 2- 2 of FIG. 1.

FIG. 3 is a fragmentary vertical cross-sectional view taken substantially on the line 33 of FIG. 2.

FIG. 4 is a partial electrical schematic diagram showing a portion of the selecting circuit employed in the chord-selecting means of FIGS. 1 to 3 and illustrating the manner of energization of selected solenoids.

FIG. 5 is a fragmentary perspective view of an autoharp provided with a modified fonn of chord-selecting means according to the present invention.

FIG. 6 is a chart illustrating the manner in which switch combinations are formed in the embodiment of FIG. 5 to select the desired chords to be played on the auto-harp, employing the modified system of FIG. 5.

FIG. 7 is a partial circuit diagram illustrating how the solenoids controlling respective stringed dampers of the auto-harp of FIG. 5 may be selectively energized by operating corresponding configurations of the control switches on the keyboard of the auto-harp.

FIG. 8 is an enlarged fragmentary perspective view of a portion of the neck of a guitar provided with an improved electromechanical fingering device according to the present invention for selecting chords to be played on the instrument.

FIG. 9 is an enlarged fragmentary perspective view of a portion of the neck of the guitar of FIG. 8, diagrammatically illustrating atypical set of solenoids employed to form a selected chord, as used in the electromechanical chord-forming device shown in FIG. 8.

Referring to the drawings, 11 designates an autoharp of conventional construction provided with respective vibratory strings 12 which are tuned to vibrate at acoustic frequencies, corresponding to the tones of a musical scale. In the conventional auto-harp there are 36 strings, each of which can vibrate to produce a particular musical tone. In accordance with the present invention a rigid frame member 13 is mounted transversely across the strings, the frame member having vertical end legs 14,14 which are suitably secured rigidly to the opposite longitudinal marginal portions of the auto-harp, the frame member 13 being located so as to overlie the intermediate portions of the vibratory strings 12, as shown in FIG. 1. Mounted in the frame member 13 over the respective strings are solenoids 15 having plungers 16 which are provided at their-bottom ends with enlarged damper elements 17 made of suitable damping material, the damper elements being formed with downwardly facing V-notches 18 which normally receive the respective strings, the members 17 being biased downwardly by coil springs 20 surrounding the associated plungers. Thus, the biasing springs 20 exert a sufficient downward force on the damper members 17 to effectively damp the vibration of the strings 12 under normal conditions, and said strings are free to vibrate only when the associated solenoids 15 are energized to elevate the dampers. Therefore, when one or more of the solenoids 15 are energized and the strings 12 are strummed, the undarnped strings will vibrate, and it is thus possible to produce chords by suitably selecting a proper combination of solenoids 15 to be energized.

As shown in FIG. 3, the frame member 13 is provided with the respective upper and lower cavities 21 and 22, the solenoids 15 being located in the lower cavity 22 and their plungers 16 extending slidably through the bottom wall 23 of cavity 22. A suitable source of current, such as a battery 25 is mounted in lower cavity 22, and various electrical components, such as diodes 35 are likewise mounted in the cavity 22, said components forming part of the control circuit for the solenoids 15, as will be presently described.

An array of push-button switches 27 is mounted on the top wall 28 of the frame member 13, each switch corresponding to a desired chord to be played. Thus, in a typical arrangement illustrated in FIG. 3, the switches have bridging poles 29 which are normally biased upwardly and which may be depressed to bridge respective pairs of switch contacts 30,30. The switches 27 are therefore normally open and may be closed by depressing their push-button elements.

Referring to FIG. 4, it will be seen that one terminal of the power source 25 is connected through a master control switch 32 to a first power supply wire 33, and that the other terminal of power source 25 is connected to a second power supply wire 34. One tenninal of each of the solenoids 15 is connected to said second power tions of a group of solenoids 15 which will become energized when the top bus bar 36 is connected to the supply wire 33 as a result of the closure of the corresponding chord-selecting push-button switch 27. The energization of the selected bus bar 36 will correspondingly cause energization of the solenoids 15 connected thereto through the associated properly poled diodes 35, whereby to elevate the dampers 17 controlled by said solenoids and to release the corresponding strings 12. In the typical configuration illustrated in FIG. 4, nine solenoids 15 will become energized by the closure of the top push-button switch 27, thereby releasing the corresponding auto-harp strings and allowing a chord to be sounded when the auto-harp is strummed, the chord being a combination of the tones generated by the nine strings.

As is further shown in FIG. 4, solenoids may be connected to various bus bars 36 through suitablypoled diodes 35, whereby the solenoids may be energized responsive to the closure of other chord-selecting switches 27. Each bus bar 36 is connected to the supply wire 33 through a respective selecting push-button switch 27. The closure of each push-button switch 27 therefore will provide energization of a particular group of solenoids, whereby to release their associated strings, to provide for the sounding of corresponding chords. Since the power source 25 is a direct current source, such as a battery, or the like, the selected solenoids ultimately will be energized, since the diodes 35 prevent energization unless the current flows in one direction. Therefore, undesired solenoids cannot be energized when a particular chord-selecting push-button switch 27 is actuated. Thus, if the second push-button switch 27 of FIG. 4 is closed instead of the top switch, only three of the solenoids, namely No. 27, No. 15 and No. 3 of the strings 12 will be released for free vibration. This provides a somewhat different chord from the one which can be generated following closure of the top push-button switch 27 Thus, in the typical embodiment illustrated in FIGS. 1 to 4, there are 39 chord-selecting individual pushbutton switches 27, each being wired to allow selection of a corresponding chord by means of its associated diode matrix. Additional chords may be added by the addition of a switch for each chord and appropriate diode connections.

FIGS. 5, 6 and 7 illustrate a modification of the chord-selecting arrangement for the auto-harp 11 wherein the transversely extending support member 13 carries a relatively small number of push-button switches 27 and the energizations of the bus bar conductors 36 associated with respective matrix circuits are effected by actuating specific combinations of the switches 27 and by the response of logic gates 37 operatively associated with the bus bar conductors 36. Thus, in the typical embodiment illustrated in FIGS. 5, 6 and 7, six selecting switches 27 are provided, the switches being of the single-pole double-throw type, thepoles of the switches being connected to the supply conductor 33. The selector switches are designated, for

example, in FIG. 7, by the alphabetical identifying symbols A to F." Theswitch poles normally engage their lower contacts, as viewed in FIG. 7, and may be actuated so that the poles engage their upper contacts. Thus, in the normal condition of the switches, their poles engage contacts connected to conductors having zero subscript designations, as illustrated in FIG. 7. Thus, the uppermost switch A normally has its pole engaging a contact connected to the conductor A and when the switch is operated, it pulls over into engagement with a contact connected to a conductor identified as A Therefore, in the normal condition of the switch A," the supply conductor 33 is connected to the conductor A whereas when the switch is operated, the supply conductor 33 is connected to the conductor A A particular combination of switches may be simultaneously operated to correspondingly connect the supply conductor 33 to a desired combination of conductors A A B B etc., providing a choice of selection of a binary type, in accordance with the table shown partially in FIG. 6. Employing the six switches 27' shown in FIGS. 5 and 7, there are 64 combinations possible. Each logic gate 37 has six inputs which are connected to selected conductors 38 connected to the contacts of the switches 27, and each logic gate 37 is an AND gate designed to conduct responsive to the energization of all of its input conductors 38. Such total energization occurs only as a result of a particular binary configuration representing a specific combination of simultaneous actuations of the switches 27', for example, in accordance with the showing of the table of FIG. 6. For example, the bus bar conductor 36, identified as M, in FIG. 7, corresponds to the bus bar conductor 36 of FIG. 4, which is energized by the closure of the top switch 27, resulting in the energization of thesolenoids 15 associated with the strings providing the E flat chord, as previously described. The input terminals of the AND gate 37 associated with the bus bar conductor M, are connected respectively to the A B C D E and F conductors 38, so that the gate conducts only in response to the actuation of the A selector switch shown in FIG. 7. As above explained, the other gates 37 have their inputs connected to different combinations of the conductors 38 so that they will conduct in response to definite combinations of simultaneous actuation of switches 27', in accordance with the table of FIG. 6. Therefore, with the arrangement shown in FIGS. 5, 6 and 7, it is possible to selectively energize the different bus bar conductors 36 by employing corresponding combinations of operation of the six selector switches 27. As above mentioned, with the use of the six switches shown, here are 64 combinations possible which may be employed to energize the solenoid matrix bus bar conductors 36 and which therefore may be employed to select any one of 64 chords.

The number of chord combinations using the binary selection mode illustrated by the table of FIG. 6 is equal to 2 to the nth power, wherein n is the number of switches 27'. Therefore, any number of switches may be used depending on the number of chord combinations desired. For example, four switches 27' may be employed to provide 16 combinations, seven switches 27 may be used to provide 128 combinations, etc. A practical limit is reached, however, which depends on the number of chords which are useful and the amount of digital components which may be economically employed. The table of FIG. 6 illustrates the combinations possible from the use of the six switches 27 shown in the typical illustrated embodiment. As above explained, the 0 condition represents the associated switch in the off" closed position, and the one condition represents the switch depressed or in the on position. The subscript l employed with the alphabetical symbol associated with a particular switch therefore represents the on condition of the switch and the 0 subscript represents the off condition of the switch, with corresponding connection to the supply conductor 33. With all the switches 27 in normal, non-actuated positions, none of the gates 37 conducts and none of the bus bar conductors 36 becomes energized. In an arrangement corresponding to that of FIGS. 1 to 4, 39 bus bar conductors 36 would be employed to provide a selection of 39 different chords. Therefore, in the modification of FIGS. 5, 6 and 7, to provide the same result, there would be 39 AND gates 37 to provide selection of the 39 different chords. Since a total of 64 combinations are possible, additional capability of chord selection may be provided by ad ding the required additional gates and connecting them to the appropriate output conductors of the switches 27'.

Referring now to FIGS. 8 and 9, there is illustrated the application of the present invention to a stringed musical instrument wherein the strings are normally open, for example, a six-stringed guitar. The guitar is of conventional construction and has the neck portion 40 over which are strung the six strings 41, the neck portion being provided with the conventional spaced transverse fret bars 42 defining the successive fret spaces 43. Suitably secured over the neck portion 40 is a rigid housing 45 in which are mounted respective solenoids 46, each solenoid being located over a string 41 and over a fret space 43, so that there are six longitudinal rows of solenoids 46 with the solenoids arranged in transverse rows over the respective fret spaces 43. The solenoids 46 are provided with plungers 37 having bottom dampers 48 which are similar to the previously described dampers 17 but which are normally maintained elevated relative to their associated strings 41 by the provision of an enlarged head element 49 on the top end of the associated plunger 47 and a coil spring 50 surrounding the upper portion of the plunger and bearing between the top wall of the solenoid 46 and its associated head 49. Energization of a solenoid causes it to move its plunger 47 downwardly and to bring its damper 48 into damping contact with the subjacent string 41, to press the string against the associated fret space 43 in the manner in which the strings are pressed downwardly by the fingers when the guitar is played manually. For example, FIG. 9 illustrates the three solenoids 36 which are energized simultaneously when a C chord is to be sounded.

The housing 45 is provided with the inclined keyboard portion 51 on which are mounted a plurality of push-button switches 52, corresponding to the pushbutton switches 27 employed in FIG. 1, the chordselecting switches 52 being incorporated in a selecting circuit similar to that shown in FIG. 4, each push-button switch 52 corresponding to a particular chord to be played. Thus, the solenoids 46 of the embodiment of FIGS. 8 and 9 are wired in a manner similar to the solenoids 15 of FIG. 4, and the circuit employed is similar to the circuit of-FIG. 4, previously described.

In the typical embodiment illustrated in FIGS. 8 and 9, 48 chords may be selected, with a corresponding number of push-button switches 52 provided on the keyboard 51. Actuation of any of the push-button switches 52 will cause energization of the solenoids 46 corresponding to the desired chord, since this will cause the associated fretting pads 48 to be lowered into fretting engagement with the strings 41 in the same manner as the fingers would be employed to form the desired chord. As in the case of the conventional manner of forming chords, the strings are strummed while the selected push-button switch 52 is held actuated.

It will be readily apparent that any desired number of chords maybe made available by suitably designing the housing 45 and making provision for the required solenoid units 46 to be mounted therein and for the required push-button switches 52 to be provided on the keyboard portion 51 of the housing.

If so desired, within the spirit of the present invention, the instrument may be provided with the chordselecting arrangement of FIGS. 5 to 7, employing a relatively small number of chord-selecting keys and the logic circuit of FIG. 7, instead of employing one individual key 52 for each chord to be selected. Thus, as in the embodiment illustrated in FIGS. 5, 6 and 7, with such an arrangement, a particular chord could be selected by actuating a combination of the selecting switches simultaneously, the switches being of the double-throw type such as the switches 27' of FIGS. 5 and 7, and being arranged in binary selector circuits provided with AND gates 37 associated with respective bus bar conductors 36, as previously described.

The housing 45 may be of any desirable shape, for example, may be of generally rectangular shape provided with a bottom longitudinal recess 54 to receive the neck portion 40 and the associated strings 41, and the housing may be fastened to the neck portion 40 in any suitable manner, for example, by conventional fasteners 55.

The use of cams, levers and other mechanical power amplifying devices actuated by solenoids or relays, which in turn are digitally controlled as previously described, is considered to be within the spirit of the present invention, and may occur to those skilled in the art as well.

The use of earns, levers, pistons, bellows and other mechanical or fluidic power amplifying devices, either actuated by controlling solenoids or relays, which in turn are digitally controlled as previously described, or the use of mechanical and fluidic control of these power amplifying devices to select the desired combinations of strings, is likewise considered to be within the spirit of the present invention and may occur to those skilled in the art as well. The word fluidic contemplates the use of any suitable liquid or gas.

While certain specific embodiments of improved chord-selecting means for stringed instruments have been disclosed in the foregoing description, it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art.

Therefore, it is intended that no limitations be placed on the invention except as defined by the scope of the appended claims.

What is claimed is:

1. in a stringed musical instrument having a plurality of tuned strings, chord-selecting means comprising a support overlying the strings, solenoids mounted on said support over the respective strings and having damper means engageable at times with the strings, a plurality of chord-selecting switches mounted on said support, a source of current, and circuit means connecting the solenoids to the source of current through the respective chord-selecting switches.

2. The stringed musical instrument of claim 1, and wherein said circuit means comprises a first supply conductor connecting one terminal of said source to one tenninal of each solenoid, a plurality of bus bar conductors corresponding to different chords, circuit means including a unidirectional conductor connecting the other terminal of each solenoid to at least one bus bar conductor, and circuit means including said selecting switchesto selectively connect the bus bar conductors to the other terminal of said source.

3. The stringed musical instrument of claim 2, wherein said source is a direct current source and said unidirectional conductors comprise diodes poled in the same direction between the solenoids and the respective bus bar conductors.

4. The stringed musical instrument of claim 3, and wherein certain of the solenoids are provided with circuit branches connecting their said other terminals to a plurality of said bus bar conductors, said circuit branches each including a similarly poled diode.

5. The stringed musical instrument of claim 4, and wherein said damper means are normally in damping engagement with the strings and release the strings for vibration responsive to energization of the solenoids.

6. The stringed musical instrument of claim 4, and wherein said damper means are normally disengaged from the strings and are moved into damping engagement with the strings responsive to energization of the solenoids.

7. The stringed musical instrument of claim 4, and wherein said support transversely overlies the tuned strings and said solenoids are arranged in at least one transverse row over the strings.

8. The stringed musical instrument of claim 4, andwherein each bus bar conductor is connected to said other terminal of the source through a respective chord-selecting switch.

9. The stringed musical instrument of claim 4, and wherein said chord-selecting switches are of the multipie-position type, and said last-named circuit means includes AND gates connected between the contacts of the switches and the respective bus bar conductors.

10. The stringed musical instrument of claim 9, and wherein said chord-selecting switches are of the singlepole. double-throw type, each having a pole and a pair of contacts, the pole being normally in engagement with one of the contacts, the contacts being connected to the input terminals of the AND gates. 

1. In a stringed musical instrument having a plurality of tuned strings, chord-selecting means comprising a support overlying the strings, solenoids mounted on said support over the respective strings and having damper means engageable at times with the strings, a plurality of chord-selecting switches mounted on said support, a source of current, and circuit means connecting the solenoids to the source of current through the respective chordselecting switches.
 2. The stringed musical instrument of claim 1, and wherein said circuit means comprises a first supply conductor connecting one terminal of said source to one terminal of each solenoid, a plurality of bus bar conductors corresponding to different chords, circuit means including a unidirectional conductor connecting the other terminal of each solenoid to at least one bus bar conductor, and circuit means including said selecting switches to selectively connect the bus bar conductors to the other terminal of said source.
 3. The stringed musical instrument of claim 2, wherein said source is a direct current source and said unidirectional conductors comprise diodes poled in the same direction between the solenoids and the respective bus bar conductors.
 4. The stringed musical instrument of claim 3, and wherein certain of the solenoids are provided with circuit branches connecting their said other terminals to a plurality of said bus bar conductors, said circuit branches each including a similarly poled diode.
 5. The stringed musical instrument of claim 4, and wherein said damper means are normally in damping engagement with the strings and release the strings for vibration responsive to energization of the solenoids.
 6. The stringed musical instrument of claim 4, and wherein said damper means are normally disengaged from the strings and are moved into damping engagement with the strings responsive to energization of the solenoids.
 7. The stringed musical instrument of claim 4, and wherein said support transversely overlies the tuned strings and said solenoids are arranged in at least one transverse row over the strings.
 8. The stringed musical instrument of claim 4, and wherein each bus bar conductor is connected to said other terminal of the source through a respective chord-selecting switch.
 9. The stringed musical instrument of claim 4, and wherein said chord-selecting switches aRe of the multiple-position type, and said last-named circuit means includes AND gates connected between the contacts of the switches and the respective bus bar conductors.
 10. The stringed musical instrument of claim 9, and wherein said chord-selecting switches are of the single-pole. double-throw type, each having a pole and a pair of contacts, the pole being normally in engagement with one of the contacts, the contacts being connected to the input terminals of the AND gates. 